The present invention relates to a coaxial electrical connector element also providing a switching function, allowing one electrical line to be switched to another electrical line.
Many constructions of such electrical connector elements, especially of the miniature type, are already known for microwave applications. A complementary connector element, the fitting of which into the connector element provides the switching function, may for example be a connector element which diverts the microwave signal from an internal antenna to an external antenna.
Known connector elements for providing a switching function comprise a central conductor, an external conducting body forming a ground contact, a contact piece and a conducting socket which can move axially, about the central conductor, between a first position, in which it bears against the central conductor on the one hand and the contact part on the other, and a second position, in which it is away from the contact piece, a return member being provided for urging the conducting socket into its first position.
The connector element is designed in such a way that, during mating with a complementary connector element, the movable conducting socket, which is normally in its first position, is pushed back into its second position and carries out the switching operation by bringing the central conductor of the connector element into electrical contact with the central conductor of the complementary connector element.
The filing company has already described in FR-A-2 720 555 a coaxial connector element of this type, in which the return member consists of a helical spring bearing, on the one hand, against an insulating body serving to keep the inner conductor in place and, on the other hand, against a bearing surface of the movable conducting socket.
For certain spring lengths, it has been found in practice that the spring, in direct contact with the movable conducting socket, acts as an internal resonator, preventing correct operation within the useful frequency range in microwave applications.
To reduce the insertion losses, it has been proposed to fit an insulating washer between the spring and the conducting socket This washer has the drawback of entailing an additional cost because of the increase in complexity of the manufacture.
It has also been proposed to electrically connect the spring constituting the elastic return member at both its ends to the central contact, the spring being in this case held in place between two shoulders of the central conductor.
This solution has the advantage of being less expensive than that using an insulating washer, but it merely mitigates the internal resonance problem by shifting the resonance to higher frequencies.
The object of the present invention is to provide a coaxial electrical connector element also providing a switching function which, while being of simple, robust and inexpensive design, avoids the above-mentioned drawbacks of the known connector elements, while still exhibiting excellent microwave behavior especially by eliminating any internal resonance.
The connector element according to the present invention is essentially characterized in that the return member consists of an elastically deformable tubular piece engaged around the central conductor, said piece being placed in the conducting body so as to be held therein by a cylindrical end part while still being able to flex elastically, by deforming radially owing to the action of the displacement of the axially movable conducting socket during mating with a complementary connector element, said socket being designed to push the free end of said tubular piece axially backward.
Preferably, the elastically deformable piece is made of an elastomer, particularly a silicon elastomer, preferably having a Shore hardness of between 50 and 80. Other materials may also be envisioned, especially polymeric materials, provided that they have comparable strength properties at the soldering temperature, maintaining elasticity properties over the entire operating range in terms of temperature and compression, and having a low compression set.
It will be understood that the elastically deformable piece of the present invention makes it possible to provide three functions which, in the known connector elements, were provided by different elements, namely the role of mechanically holding the central conductor in position in the conductor body, which role was previously fulfilled by an insulating body, the dielectric role for transmitting the microwave signal, previously fulfilled by the insulating body, and the role of the actual return member, intended to make the axially movable socket come into contact with the contact piece when the complementary connector element is not mated.
The axially movable socket includes, in a first embodiment, a collar against which the free end of the elastically deformable piece butts, the socket having a sleeve part engaged in the end of the elastically deformable piece, allowing it to slide along the central conductor.
In a second embodiment, the movable socket consists of a disk-shaped piece having a central bore, having a diameter very slightly greater than the diameter of the central conductor in order to allow sliding along the central conductor and electrical contact with the latter when the socket is pushed back owing to the effect of the bearing of the deformed end of the elastically deformable piece.
The latter is, in a cylindrical part on the other side from its free end, drilled with a hole for passage of the inner conductor, this hole possibly being produced during molding or being pierced by the tip of the central conductor itself during manufacture of the connector element.